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Abstract:

A fuselage segment of an aircraft fuselage is provided with an outer skin
and an inner skin that are spaced apart from one another by a core,
wherein conduits for system installations are integrated into the core,
as well as a method for manufacturing such a fuselage segment.

Claims:

1. A fuselage segment of an aircraft fuselage, comprising: an inner skin
on a cabin side; and an outer skin that cover a core, wherein conduits
for system installations are integrated into the core.

2. The fuselage segment according to claim 1, wherein the inner skin and
the outer skin are realized separately of the core.

3. The fuselage segment according to claim 1, wherein the fuselage
segment is realized in one piece.

4. The fuselage segment according to claim 3, wherein a hardness of the
material of the core increases from a region on a side of the inner skin
in a direction of the outer skin.

5. The fuselage segment according to claim 1, wherein the core consists
of a multilayer foam material.

6. The fuselage segment according to claim 1, wherein the conduits
consist of tubular elements.

7. The fuselage segment according to claim 1, wherein the conduits are
integrated into the core in such a way that their wall is formed by the
core material.

8. The fuselage segment according to claim 1, wherein the inner skin
forms a sidewall of a cabin.

9. A method for manufacturing a fuselage segment according to claim 1,
wherein the conduits are produced in the core during the manufacture of
the core or after the manufacture of the core.

Description:

[0001] The invention pertains to a fuselage segment of an aircraft
fuselage according to the preamble of claim 1 and to a method for
manufacturing such a fuselage segment.

[0002] A known fuselage segment is disclosed in DE 10 2007 003 275 A1 of
the applicant. This fuselage segment is realized in the form of a shell
element with two CFRP-skins, between which a core with a honeycomb
structure or a foam structure is arranged. The shell element forms an
aircraft fuselage together with a plurality of similar shell elements,
wherein this aircraft fuselage is reinforced with a plurality of
stringers and frames for stabilization purposes. All conduits for system
installations such as, for example, electrical cables and
air-conditioning ducts are respectively mounted on corresponding brackets
of the stringers and frames.

[0003] In this solution, it is disadvantageous that equipment systems and
cabin elements are installed separately in the primary structure. The
mounting of the conduits requires numerous brackets that increase the
cost of the fuselage assembly. Furthermore, the brackets
disadvantageously affect the weight of the aircraft.

[0004] It is the objective of the present invention to develop a fuselage
segment of an aircraft fuselage that eliminates the aforementioned
disadvantages and allows a simplified assembly, as well as a method for
manufacturing such a fuselage segment.

[0005] This objective is attained with a fuselage segment with the
characteristics of claim 1 and a method according to claim 10.

[0006] An inventive fuselage segment features a core that is covered by an
inner skin on the cabin side and an outer skin. According to the
invention, ducts for system installations are integrated into the core.

[0007] The inventive solution provides the advantage that brackets are no
longer required for mounting conduits such as, e.g., air-conditioning
ducts. The assembly of the aircraft fuselage therefore becomes less
complex. In addition, the elimination of the brackets lowers the weight
of the aircraft in comparison with known aircraft with bracket solutions.
For example, electromagnetic interactions between current-carrying cables
can be prevented by accordingly positioning the conduits relative to one
another. The elimination of the brackets also makes it possible to lower
the assembly and manufacturing costs. The inventive fuselage segment may
furthermore be realized in such a way that stringers and frames or other
longitudinal and circumferential reinforcements of the aircraft fuselage
can be eliminated, wherein this also positively affects the assembly and
the weight of the aircraft. With respect to its structure, the fuselage
segment can be optimized in accordance with the occurring loads.

[0008] In one exemplary embodiment, the fuselage segment is composed of
several parts. In this case, the core is manufactured separately of the
outer skin and the inner skin. The core has, for example, a honeycomb
structure.

[0009] In another exemplary embodiment, the fuselage segment does not have
a sandwich structure, but rather a one-piece foam structure, in which the
inner skin, the outer skin and the core are realized in one piece. This
means that the inner skin and the outer skin are not bonded to the core
or otherwise connected to the core, but created during a manufacturing
step of the core. In other words, the inner skin and the outer skin
consist of the same foam material that is sectionally subjected to a
different type of treatment. In this exemplary embodiment, it is
advantageous to reinforce the foam material with carbon fibers such that
the carbon fiber reinforcement effectively extends through the core from
the outer skin to the inner skin.

[0010] The material of the core and the material of the outer skin and the
inner skin may have a different hardness. It is particularly advantageous
if the hardness of the core'material increases from a region on the cabin
side in the direction of the outer skin. In this way, the stability of
the fuselage segment can be increased and the insulation can be improved
due to the reduced hardness of the material in the region on the cabin
side.

[0011] The core may consist of a multilayer foam material such that a
purposeful insulation can be achieved. Condensation within the fuselage
segment can be significantly reduced with a sensible configuration of the
foam material because erratic temperature gradients hardly occur.

[0012] In one variation, the conduits consist of tubular elements.

[0013] In order to additionally lower the weight of the aircraft, the
conduits are in another variation integrated into the core in such a way
that their wall is formed by the core material.

[0014] The inner skin may form a side wall of the cabin. The realization
of the side wall in the form of a component of the primary structure
reduces the number of cabin components such that the assembly becomes
even less complex.

[0015] According to an exemplary embodiment of the inventive method, the
conduits are produced in the core during the manufacture thereof.

[0016] According to another exemplary embodiment, the conduits are
produced in the core after the manufacture thereof. In this case, the
conduits are respectively substituted or replaced with suitable filler
materials during the manufacture of the core. The filler materials are
removed from the core after the manufacture thereof such that the core
material itself forms the walls of the conduits. The fillers may consist,
for example, of wax-based tubular bodies that liquefy and flow out of the
core during a corresponding treatment after the manufacture thereof such
that a conduit in the form of a correspondingly shaped hollow space is
created in the core.

[0017] According to another inventive method, the inner skin, the outer
skin and the core already have their final structure with the required
material properties and material structures after the removal of the
fuselage segment from the moulding tool.

[0018] However, it is also possible to provide the foam material and, in
particular, the inner skin and the outer skin with the required material
properties such as, for example, the corresponding degree of hardness in
a step that is carried out after the removal of the fuselage segment from
the moulding tool. It would be conceivable, for example, to carry out a
treatment under UV-light.

[0019] A plastic-based material, as well as a metal-based material, may be
considered as suitable foam material. Likewise, the materials of the
inner skin and the outer skin are not limited to CFRP-materials, but may
also consist of other fiber-reinforced composite materials such as glass
fiber-reinforced materials (GFR-materials), plastic-metal alloys or pure
metal alloys. It would furthermore be conceivable that the inner skin and
the outer skin consist of different materials.

[0020] The conduits are not limited to the aforementioned examples only,
but rather may also be used for all systems to be installed in an
aircraft. Other examples are electrical cables for the power supply of
the airborne supply system, signal lines for the flight control and water
conduits.

[0021] Openings for windows and doors are either created during the
manufacture of the fuselage cell or subsequently produced in the fuselage
cell.

[0022] The axial length of the fuselage segment and its circumference may
vary. It would be conceivable to realize the fuselage segment in the form
of a shell element that, in principle, extends over the entire length of
the aircraft. It would likewise be conceivable to realize the fuselage
segment in the form of a barrel element that can be joined into an
aircraft fuselage by means of transverse butt joints (cross butt joints).

[0023] Other advantages exemplary embodiments of the invention form the
objects of the dependent claims.

[0024] Preferred exemplary embodiments of the invention are described in
greater detail below with reference to a schematic drawing.

[0025] The only FIG. 1 shows a cross section through an inventive fuselage
segment 2 of an aircraft fuselage. The fuselage segment 2 is realized in
the form of a curved shell element of sandwich construction with an inner
skin 4 and an outer skin 6, between which a core 8 is arranged. In the
region of its narrow sides 10, 12, the fuselage segment 2 and other
not-shown inventive fuselage segments are assembled into a barrel-shaped
fuselage.

[0026] The inner skin 4 forms a sidewall of an aircraft cabin. The outer
skin 6 serves as the common outer surface of an aircraft fuselage and
protects the core 8 from environmental influences. The inner skin 4 and
the outer skin 6 consist of a carbon fiber-reinforced material
(CFR-material) and are connected to the core 8. The material of the inner
skin 4 and the outer skin has a higher hardness than that of the core 8.

[0027] The core 8 consists of a foam material and features a radially
inner layer 14 and a radially outer layer 16. The hardness of the
radially inner layer 14 is lower than that of the radially outer layer 16
in order to improve the insulation.

[0028] Conduits 20, 22 for system installations such as, for example,
current-carrying cable harnesses, cable harnesses that carry data signals
or air-conditioning ducts are integrated into the core 8. Only two
conduits 20, 22 are identified by reference symbols in FIG. 1 and
representative for all other conduits. The conduits 20, 22 are realized
in the form of tubular elements 24, 26 produced in the core 8. With
respect to their position in the core 8 and their inside diameter, they
correspond to their respective function. Conduits 20 for accommodating
cable harnesses that carry data signals generally have a smaller inside
diameter than conduits 22 that form air-conditioning ducts.

[0029] The degrees of hardness of the inner skin 4, the outer skin 6 and
the core 8 are chosen such that no stringers and frames or other types of
longitudinal and circumferential reinforcements are required for creating
the aircraft fuselage.

[0030] In an inventive method, the tubular elements 24, 26 for the
conduits 20, 22 are positioned in a moulding tool for moulding the core
8. Subsequently, the mould is filled with a suitable plastic-based raw
material in order to create the core 8. The moulding tool is then
activated in such a way that the foam-like core 8 is formed. The inner
skin 4 and the outer skin 6 are manufactured in conventional fashion.
After the manufacture of the core 8, the inner skin 4 and the outer skin
6, they are correspondingly connected to one another.

[0031] The invention discloses a fuselage segment 2 of an aircraft
fuselage with an outer skin 6 and an inner skin 4 that are spaced apart
from one another by a core 8, wherein conduits 20, 22 for system
installations are integrated into the core 8, as well as a method for
manufacturing such a fuselage segment 2.